That's correct. When the Bose QC2 battery is dead, the headset is dead. I'll bet the Bose pilot version does the same thing. Interestingly, the boom mic works though. When I first put the headset on, I tap the squelch just to make sure I hear something. When I first used them, I figured I would wait until it failed to change the battery; now I just use a a fresh one each trip. With a single fresh AAA battery, it has always lasted the entire trip.whiff said:Do you mean w/out a battery you can't hear anything on the headset or that the noise cancelling function goes away? I have a telex ANR now and if the battery dies it still works - just gets kinda load.